When a silver halide photographic material is exposed to light and is subjected to color development, dye-forming couplers (hereinafter referred to as couplers) react with the oxidized aromatic primary amine developing agent and color images are formed. Generally, in this method, the color reproduction technique by the subtractive process is used, and in order to reproduce blue, green, and red, color images of yellow, magenta, and cyan complementary to them are formed. In the formation of a cyan color image, phenol derivatives or naphthol derivatives are used as coupler in many cases. In color photography, color-forming couplers are added into a developing solution or are contained in photosensitive photographic emulsion layers or other color-image-forming layers, and the color-forming couplers react with the oxidized product of a color-developing agent formed by the development, thereby forming nondiffusing dyes.
The reaction of a coupler and a color-developing agent takes place at the active site of the coupler, and couplers having a hydrogen atom at that active site are four-equivalent couplers, that is, those couplers that stoichiometrically require four mols of a silver halide having development nuclei to produce 1 mol of a dye. On the other hand, couplers having a coupling releasable group as an anion at the active site are two-equivalent couplers, which stoichiometrically require only two mols of a silver halide having a development nuclei to form 1 mol of a dye. Therefore, in contrast to four-equivalent couplers, two-equivalent couplers generally allow the amount of a silver halide in a photographic layer to be reduced to make the film thinner, the time required for the processing of the photographic material can be made shorter, and further the sharpness of the formed color image is improved.
Of the various cyan couplers, naphthol couplers have hitherto been used widely in photography mainly in color negative films, since the wavelength of the absorption of the produced dye image is sufficiently long, and therefore the absorption less overlaps with the absorption of the magenta dye image, and also the coupling reactivity with the oxidized product of a color developer can be selected to range from a lower one to the higher one. However, since the dye image obtained from naphthol couplers is apt to be reduced with bivalent iron ions built up in an exhausted bleaching solution or bleach-fix solution and to fade (which is referred to as reduction fading), and it is poor in heat fastness, improvement is earnestly desired.
On the other hand, U.S. Pat. No. 4,333,999 discloses phenol cyan couplers having in the 2-position a p-cyanophenylureido group and in the 5-position a carbonamido group that is a ballasting group (diffusion-resistance-providing group). These couplers have come into wide use for said naphthol cyan couplers, since the dye associates in the film, thereby causing a bathchromic shift, which gives a dye image that is excellent in hue and fastness.
However, the performance required for recent photographic materials is severe, and even these couplers are continuously required to have higher coupling reactivity, higher dye absorption density, more excellent color purity, and more excellent fastness of the dye image. To meet these requirements, various studies concerning the 5-position ballasting group have been made and various couplers are disclosed, for example, in JP-A ("JP-A" means unexamined published Japanese patent application) Nos. 105644/1984, 111643/1984, and 111644/1984, U.S. Pat. Nos. 4,753,871, 4,775,616, and 4,849,328, and European Patent Application No. 271,323A. However, even if high coupling reactivity and high dye absorption density were satisfied, the wavelength of the absorption was too short, or even if high dye absorption density and excellent color purity were satisfied, fastness of the dye image was poor, or even if excellent color purity and excellent fastness of the dye image were satisfied, the dye absorption density was low, and therefore it was difficult to satisfy all the requirements.